582 PROCEEDINGS OF THE NATIONAL MVSEVM. vol. xxxii. 



crassispinis. It is possible that two or more species of the genus 

 Aeanthion are found on Borneo; but at present there is nothing in the 

 literature to show this fact satisfactoril}^ or to indicate what their 

 characters are. 



THECURUS, new genus. 



Family. — Hystricida^ subfamily Hystricina?. 



Type. — Thecurus sumatrce., new species. (Description on page 588.) 



Speciefi. — The type species is the only known one in the genus so far 

 as known. 



Diagnostic characters. — Externally like a small Acanthion.^ but cap- 

 sule-like ends of caudal hairs, smaller and relatively shorter, often 

 closed at the ends (Plate LVII, fig. 2), quills smaller, and replaced on 

 lower rump by grooved spines similar to those on upper back. Crani- 

 ally very similar to the genus AtJierurus, but brain-case relatively 

 wider, rostrum narrower, and no well-marked fossa on outer side of 

 mandible just beneath condj^lo-coronoid notch; molars rootless. 



E;cternal characters. — About half the size of Acanthion., to which it 

 has a striking resemblance, but it has no bristly hairs on the head or 

 neck, but merely soft, flattened spines. The flattened spines extend 

 farther down the back than they do in Acanthion and are more con- 

 spicuously grooved, and they are also found on the lower back and 

 rump instead of the short quills of Acanthion. The large lieavy 

 quills occupy about the third fourth of the back. They are much less 

 numerous and shorter than those of Acanthion.^ the largest not exceed- 

 ing 150 mm. These quills are dark in color, with a light base and 

 apex. A very few long stifl' bristles are interspersed among the quills. 

 Some short quills are found on the base of the tail, while the terminal 

 portion of that organ is covered with peculiar modified hairs, but the 

 capsules are relatively much shorter and a great many more of them 

 are closed at the apex — drawn out to a point. (Plate LVII, fig. 2.) 

 The sides of the head, the underparts, and the legs, are in general 

 clothed with rather soft, flattened, grooved spines. 



SJceletoii. — The main features of the skull of the genus Thecurus 

 have previousl}^ been pointed out. The relative size and shape of the 

 skull and its vai'ious parts are clearly shown in fig. 1, Plates LIV, LV, 

 and LVI, so that no detailed description is here necessary. The verte- 

 bral formula is: Cv. 7, D. 14, L. 5, S. 4, Cd. 17. Although the skele- 

 ton of Thecurus as a whole, aside from the skull, is in general strikingly 

 like that of Acanthion, yet in one or two points it is quite different. 

 Instead of having a large, laterally compressed neural spine on the 

 axis, that vertebra bears a relativel}" short, tri-prismatic spine, not com- 

 pressed laterall}' an}^ more than it is antero-posteriorly. (Plate LVII, 

 fig. 9.) The seventh cervical vertebra in Thecurus has no long neural 

 spine. The long neural spine on the seventh cervical seen in Acayi- 



